JP2001177551A - System and method for redundant optical multiple branch communication - Google Patents

Abstract

PROBLEM TO BE SOLVED: To perform high-speed switching of transmission lines involved in the switching of a master station side devices of an active system and a reserve system when the master station side device of an optical multiple branch communication system has a redundant configuration. SOLUTION: The inter-system delay difference setting parts 17a and 17b of the respective slave station side devices 10a and 10b of an active system and a reserve system hold the inter-system delay difference which is outputted from the devices 10a and 10b via a light splitter 30, made to return at each of slave station side devices 20-1 to 20-n and corresponds to time difference transferred to the devices 10a and 10b, delaying parts 19a and 19b delay an optical signal to be transmitted to the devices 20-1 to 20-n in accordance with the inter-system delay difference and transmits the optical signal when the device 10b of the reserve system is switched over to the active system, and delay quantity correcting parts 14a and 14b apply preliminarily corrected setting to delay quantity set by the devices 20-1 to 20-n in accordance with the inter- system delay difference when the device of the reserve system 10b is switched over to that of the active system.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an OLT (Optical Line Terminatio)
n) and a plurality of slave units (ONU: Optical Network Uni)
t) are connected by an optical splitter, and at least the working and standby master stations are redundantly connected by one or more optical communication lines, and the working master station is connected to each other by the optical splitter. Broadcasting and distributing the optical signal to the slave device, the working master device measures the round trip time for each slave device, and notifies the slave device to the round trip time. A redundant multi-branch communication system and a method thereof, in which each of the slave stations sets an optical signal transmission timing corresponding to each of the notified round trip times to be time-division multiplexed connected to the working master station. More particularly, the present invention relates to a redundant multi-branch communication system and a method thereof that can quickly switch from an active master station device to a standby master station device.

[0002]

2. Description of the Related Art Conventionally, there is an optical multi-branch communication system in which a master station device and a plurality of slave station devices are connected by optical fibers. FIG. 11 is a block diagram showing a schematic configuration of an optical multi-branch communication system in which one master device and a plurality of slave devices are connected by an optical fiber. The system shown in FIG. 11 is based on ITU-T (International Telecommunication Union-Telecomm).
unication) Recommendation G. 983.1 shows a configuration of an optical multi-branch communication system defined in 983.1. In FIG. 11, one master station apparatus 110 and a plurality of slave station apparatuses 120-1 to 120-1 are illustrated.
120-n is connected via the optical splitter 130.

[0003] ITU-T Recommendation G. In 983.1, the downstream optical signal from the parent device 110 is transmitted to the optical splitter 130.
, And the upstream optical signals from each of the slave station devices 120-1 to 120-n are multiplexed by the optical splitter 130 and are multiplexed. Sent to 110. At this time, access control for multiplexing the upstream optical signals from each of the optical network units 120-1 to 120-n, that is, delay control, is performed on the optical splitter 130. This delay control is also described in ITU-T Recommendation G. 983.1.

FIG. 12 is a block diagram showing a detailed configuration of a conventional optical multi-branch communication system. The optical multi-branch communication system 100 shown in FIG. 12 executes a sequence called ranging at the time of power-on or the like. In the ranging sequence, first, in the master station device 110, the delay amount measurement cell generation unit 115 transmits the specific slave station devices 120-1 to 120-1.
A delay amount measurement cell is generated for 120-n. Each of the generated delay amount measuring cells is stored in an OAM (maintenance and operation management: Oper).
ation Administration and Maintenance) Cell insertion unit 1
At 16, it is multiplexed as OAM cells in the downlink main data, and the optical transceiver and WDM (frequency multiplexing method: Wave)
length division multiplexing) in the transmitting / receiving section 111 constituted by a coupler or the like.
0-n.

In each of the slave station devices 120-1 to 120-n, an optical transceiver (not shown) and a W
The optical signal received by the DM coupler or the like is converted into an electric signal. The converted electric signal is transmitted to the frame synchronization unit 12.
In step 2, frame synchronization is established based on the frame synchronization bits in the OAM cells periodically inserted, and the boundaries between the cells are recognized. The OAM cell separation unit 123 identifies and separates a data cell and an OAM cell addressed to the local station device 120-1. When the delay amount measurement cell among the separated OAM cells is input, the delay amount setting unit 124 immediately notifies the OAM cell insertion unit 126 and transmits the delay amount measurement cell as a response to the transmission / reception unit 121, the optical splitter 130, or the like. Is transmitted to the parent station side device 110 via That is, when receiving the delay amount measurement cell, the slave station device 120-1 immediately returns and sends it to the master station device 110.

[0006] On the other hand, the OAM cell separation unit 112 of the master station device 110 separates the data cells and the OAM cells. When the OAM cell separated by the OAM cell separation unit 112 includes the delay amount measurement cell,
The round trip time is measured based on the response from the delay amount measurement cell. The round trip time is one round trip time until a cell transmitted from the master device 110 returns to the slave device 120-1 via the optical splitter 130 and is returned to the master device 110 again. Say. The delay amount measurement cell generation unit 115 calculates the delay amount between the master device 110 and the slave device 120-1 based on the round trip time, and notifies the delay amount including the information of the delay amount. A cell is generated and transmitted to the OAM cell insertion unit 111.
The OAM cell insertion unit 111 sets the delay amount notification cell to OA
The slave station side device 1 is included in the M cell
20-1.

[0007] The OAM cell separation unit 123 of the slave unit 120-1 that has received the cell including the delay amount notification cell separates the OAM cell as described above and sets the delay amount setting unit 124.
Sets the delay amount as a control amount of the reading time for the buffer memory 125 when the OAM cell includes the delay amount notification cell. As a result, the transmission timing from the plurality of slave station apparatuses to the master station apparatus is set in each slave station apparatus in consideration of the delay time, multiplexing is performed in an orderly manner, and uplink optical transmission is performed normally. Will be.

[0008]

By the way, ITU-T
Recommendation G. 983.1 also defines a redundant optical multi-branch communication system in which the master station device is redundantly configured as shown in FIG. In this redundant optical multi-branch communication system, a master device 110a as a working system and a master device 110b as a standby system are connected to the optical splitter 130 instead of the master device 110 shown in FIG. Configuration. The optical splitter 130 and the master-station-side devices 110a and 110b are connected by optical fibers.

In this redundant optical multi-branch communication system,
When the switching of the master-station-side devices 110a and 110b occurs, the master-station-side device 110b that has been switched to the active system is connected to each of the slave-station-side devices 120-1 to 120 in the same manner as when the system is started.
-N, the delay amount must be measured again, and re-ranging for setting the delay amount in each of the local station devices 120-1 to 120-n must be performed. There is a problem that the interruption time becomes long and high-speed switching cannot be performed.

[0010] The present invention has been made in view of the above,
Redundant optical multi-branch communication that can perform high-speed transmission path switching accompanying switching of the active-system and standby-system devices when the master device of the optical multi-branch communication system has a redundant configuration. It is intended to obtain a system and a method thereof.

[0011]

In order to achieve the above-mentioned object, a redundant optical multi-branch communication system according to the present invention comprises an optical splitter in which an active system and a standby system have a master station apparatus and a plurality of slave station apparatuses. Connected, and at least the working system and the protection system master device are redundantly connected by one or more optical communication lines, and the working system master device is connected to each slave device by the optical splitter. The active master station device measures the round trip time for each slave station device, notifies the round trip time to each slave station device, and transmits the round trip time to each of the notified round trip times. Correspondingly, in the redundant optical multi-branch communication system in which each of the slave station devices sets the transmission timing of the optical signal to be time-division multiplexed connected to the working master station device, parent The back-end device returns the round trip optical delay time from the working master device to the slave device via the optical splitter and transfers it back to the working master device, and the standby master device. Holding means for holding an optical delay time difference from the round trip optical delay time which is returned from the local device via the optical splitter to the slave device and transferred to the standby system again in the standby system; Transmission control means for transmitting an optical signal to be sent to each slave station device when the office device has been switched to the working system by delay correction corresponding to the optical delay time difference, and sending the optical signal; Delay amount correction means for setting a delay amount for each of the slave station side devices in advance when the side device is switched to the active system, in accordance with the optical delay time difference. .

According to the present invention, the holding means of the active system and the standby system of the master device are arranged such that the working system and the standby system of the master device are transmitted from the working master device via the optical splitter. And return to the working-side master device, the round trip optical delay time transferred to the working master device again, and the back-up master device via the optical splitter. An optical delay time difference from the round trip optical delay time transferred to the standby master station device is held, and the transmission control means is configured such that when the standby master station device is switched to the working system, each slave station device is transmitted. The optical signal to be transmitted to the optical delay time is transmitted after performing the delay correction corresponding to the optical delay time difference, the delay amount correction means,
When the master device of the standby system is switched to the working system, the delay amount for each slave station device is set to be corrected in advance in accordance with the optical delay time difference. When the switching is performed, the delay difference between the upstream and downstream directions is corrected, and normal optical multi-branch communication is performed without performing re-ranging.

[0013] In the redundant optical multi-branch communication system according to the next invention, in the above invention, the transmission control means includes a frame counter, and when the own parent station device is a standby system, the transmission control means includes a frame counter. The frame counter is subordinately synchronized with the frame counter of the active master device, and runs when the own master device is switched to the active system. The phase of the frame counter is delayed in accordance with the optical delay time difference, and the optical signal is transmitted in synchronization with the delayed frame counter.

According to the present invention, the transmission control means includes a frame counter, and when the own master station apparatus is the standby system, the frame counter of the own master station apparatus is used to change the frame counter of the working master station apparatus. The slave station synchronizes with the counter and runs when the own master station apparatus is switched to the working system, and the transmission control means of the standby system delays the phase of the frame counter of the standby system in accordance with the optical delay time difference. An optical signal is transmitted in synchronization with the delayed frame counter.
Delay correction is performed to match the downstream transmission timing at the position of the optical splitter.

[0015] In the redundant optical multi-branch communication system according to the next invention, in the above invention, the transmission control means includes a memory in front of the transmission means for transmitting the optical signal, and the transmission control means includes the memory. The transmission timing of the optical signal is delayed in accordance with the optical delay time difference by controlling the amount of memory.

According to the present invention, the transmission control means includes a memory in front of the transmission means for transmitting the optical signal, and the transmission control means controls the amount of memory in the memory to thereby adjust the transmission timing of the optical signal. The delay is delayed in accordance with the optical delay time difference, and a delay correction is made to match the downstream transmission timing at the position of the optical splitter.

In the redundant optical multi-branch communication system according to the present invention, the active and standby master stations and a plurality of slave stations are connected by an optical splitter, and at least the active and standby masters are connected. The optical line terminal is redundantly connected by at least one optical communication line, and the working master optical device broadcasts and distributes an optical signal to each slave optical device by the optical splitter.
The working master device measures the round trip time for each slave device, notifies the slave device to the round trip time, and responds to the notified round trip times. In the redundant optical multi-branch communication system in which the slave station device sets the transmission timing of the optical signal by time-division multiple access to the working master device, the working and protection master devices are: The round trip optical delay time from the working master station device via the optical splitter to the slave station device via the optical splitter and transferred again to the working master device, and the standby master device from the protection system. Holding means for holding the optical delay time difference between the round trip optical delay time and the round trip optical delay time transferred back to the standby-system side device via the optical splitter and transferred again to the standby-system side device; Switch to working system Notification means for notifying the information including the optical delay time difference to each slave station side device in the case of being notified, wherein each slave station side device has a delay amount in consideration of the optical delay time difference notified by the notification means. And delay control means for controlling the transmission timing of the optical signal to be transmitted to the master station side device.

According to the present invention, the holding means of the active and standby master devices is turned back by the slave device from the working master device via the optical splitter, and the working device is restored again. The round trip optical delay time transferred to the master unit of the system and the round trip transmitted from the master unit of the standby system to the slave unit via the optical splitter and transferred again to the master unit of the standby system Hold the optical delay time difference from the optical delay time,
Notifying means notifies each slave station apparatus of information including the optical delay time difference when the standby master station apparatus is switched to the working system, and the delay control means of the slave station apparatus determines the notification. Resets the delay amount taking into account the optical delay time difference notified by the means, controls the transmission timing of the optical signal to be transmitted to the master station side device, and delays in the downlink direction when the working system and the protection system are switched. The difference is corrected for delay by frame resynchronization, the delay difference in the upstream direction is corrected by delay control means,
Normal multi-branch optical communication is performed without re-ranging.

[0019] In the redundant optical multi-branch communication system according to the next invention, in the above invention, when each of the slave station devices receives the information including the optical delay time difference, the information is transmitted from the master station device. It is characterized by further comprising reset means for resetting frame synchronization for receiving an optical signal.

According to the present invention, when the reset means of each slave station device receives the information including the optical delay time difference, it forcibly resets the frame synchronization for receiving the optical signal transmitted from the master station device. Then, frame resynchronization is performed after switching.

[0021] In the redundant optical multi-branch communication system according to the next invention, in the above invention, each of the master station devices further comprises an insertion means for inserting order information of the transmission cell into a transmission cell. The station-side device, inspection means for extracting the order information in the received cells and inspecting the order of each cell, and discarding means for discarding the duplicated cells when the order of the cells is duplicated by the inspection means, Is further provided.

According to the present invention, the insertion means of each master station device inserts the order information of the transmission cell into the transmission cell, and the inspection means of each slave station device checks the order information in the received cell. Is extracted to check the order of each cell, and the discarding unit discards the duplicated cell when the order of the cells is duplicated by the checking unit.

In the redundant optical multi-branch communication method according to the next invention, the active and standby master stations and a plurality of slave stations are connected by an optical splitter, and at least the active and standby masters are connected. The optical network unit is redundantly connected by one or more optical communication lines, and the working master device broadcasts and distributes an optical signal to each slave device by the optical splitter. The side device measures a round trip time for each slave station device, notifies the round trip time to each slave station device, and in response to each of the notified round trip times, each slave station device transmits an optical signal. In the redundant optical multi-branch communication method which is time-division multiplexedly connected to the active master station device by setting the transmission timing of the slave station, the slave station side from the active master station device via the optical splitter. Wrap at device The round trip optical delay time transferred again to the active master device and the standby master device from the standby system are looped back by the slave device via the optical splitter, and again to the standby master device. A holding step of holding an optical delay time difference between the transferred round trip optical delay time and the delay amount for each slave station side device when the standby system master device is switched to an active system to the optical delay time difference. A delay amount correcting step of performing a setting for performing correction in advance, and an optical signal to be transmitted to each slave station side device when the standby master station device is switched to a working system, corresponding to the optical delay time difference. A transmission control step of performing the delay correction performed and transmitting, and correcting the delay amount set in the delay amount correction step based on the delay amount of the optical signal transmitted from each of the slave station-side devices, and Notification step of notifying the slave station side device And wherein the door.

According to the present invention, in the holding step, the round trip light transmitted from the working master station device back to the slave master device via the optical splitter and transferred to the working master device again through the optical splitter. The optical delay time difference between the delay time and the round-trip optical delay time which is returned from the standby master device via the optical splitter to the slave device via the optical splitter and transferred again to the standby master device is held. In the delay amount correcting step, when the standby system of the standby system is switched to the active system, the delay amount for each of the slave devices is set to be corrected in advance in accordance with the optical delay time difference, and transmitted. By the control step, an optical signal to be sent to each slave station side device when the standby side master station side device is switched to the working system is sent out after performing delay correction corresponding to the optical delay time difference, and Depending on the process, The delay amount set in the delay amount correction step is corrected based on the delay amount of the optical signal sent from the optical line terminal, and the delay amount is notified to each of the slave side devices, and the active system and the standby system are switched. In such a case, the delay difference between the up direction and the down direction is corrected, and normal optical multi-branch communication is performed without performing re-ranging.

In the redundant optical multi-branch communication method according to the next invention, in the above invention, in the transmission control step, when the own master station apparatus is a standby system, the frame counter of the own master station apparatus is used for the working system. Subordinately synchronizes with the frame counter of the master station side device, when the self master station side device is switched to the active system, self-runs, and makes the phase of the frame counter of the master station side device correspond to the optical delay time difference. And transmitting the optical signal in synchronization with the delayed frame counter.

According to the present invention, the transmission control step synchronizes the frame counter of the own master station apparatus with the frame counter of the current master station apparatus when the own master station apparatus is the standby system, When the own master station apparatus is switched to the active system, it runs by itself, delays the phase of the frame counter of the own master station apparatus in accordance with the optical delay time difference, and synchronizes with the delayed frame counter. An optical signal is transmitted, and before and after the switching, delay correction is performed so that the downstream transmission timing at the position of the optical splitter is matched.

[0027] In the redundant optical multi-branch communication method according to the next invention, in the above-mentioned invention, the transmission control step includes controlling a memory amount of a memory for storing the transmission information to control an optical signal having the transmission information. The transmission timing is delayed according to the optical delay time difference.

According to the present invention, the transmission control step delays the transmission timing of the optical signal having the transmission information in accordance with the optical delay time difference by controlling the memory amount of the memory storing the transmission information, Delay correction is performed to match the downstream transmission timing at the position of the optical splitter.

In the redundant optical multi-branch communication method according to the next invention, in the above-mentioned invention, the active and standby master devices and a plurality of slave devices are connected by an optical splitter.
At least one of each of the active and standby master stations is one.
The above-mentioned optical communication line is redundantly connected, and the working-side master station device broadcasts and distributes an optical signal to each slave station device by the optical splitter, and the working master device is connected to each slave station. The round-trip time for the side device is measured, the round-trip time is notified to each slave device, and the slave device sets the transmission timing of the optical signal in accordance with the notified round-trip time. In the redundant optical multi-branch communication method, which is time-division multiplexedly connected to the working master station device, the working master device is turned back by the slave device via the optical splitter, and is re-established. The round trip optical delay time transferred to the active master device and the standby master device from the standby system are looped back by the slave device via the optical splitter and transferred again to the standby master device. Round trip optical delay time A holding step of holding the optical delay time difference, and when the standby system master device is switched to the working system, the standby master device sends information including the optical delay time difference to each slave device. A notification step for notifying, and a delay for controlling the transmission timing of the optical signal to be transmitted to the master station side apparatus by resetting the slave station side apparatuses to a delay amount in consideration of the optical delay time difference notified by the notification step. Control process;
It is characterized by including.

According to the present invention, in the holding step, the round trip light transmitted from the working master device to the slave device via the optical splitter is returned from the working master device and transferred to the working master device again. The optical delay time difference between the delay time and the round-trip optical delay time which is returned from the standby master device via the optical splitter to the slave device via the optical splitter and transferred again to the standby master device is held. In the case where the standby system is switched to the active system by the notification step, the standby system of the standby system notifies each slave station of information including the optical delay time difference, and controls the delay. By the step, each slave station side device resets the delay amount taking into account the optical delay time difference notified by the notification step, and controls the transmission timing of the optical signal to be transmitted to the master station side device, thereby, The active system and the standby system are disconnected In the case of a change, the delay difference in the downstream direction is corrected by the frame resynchronization, the delay difference in the upstream direction is corrected by the delay control process, and normal optical multi-branch communication is performed without performing re-ranging. .

[0031] In the redundant optical multi-branch communication method according to the next invention, in the above invention, when each of the slave station devices receives the information including the optical delay time difference, each slave station device is connected to the master station. The method further includes a reset step of resetting frame synchronization for receiving an optical signal transmitted from the side device.

According to the present invention, when each slave device receives information including the optical delay time difference in the reset step, each slave device receives the optical signal for transmitting the optical signal transmitted from the master device. The frame synchronization is reset, and the frame is resynchronized after switching.

[0033] In the redundant optical multi-branch communication method according to the next invention, in the above invention, each of the master station devices includes an insertion step of inserting order information of a transmission cell; A step of extracting the order information in the selected cells and checking the order of each cell, and a step of discarding the duplicated cell when each of the slave station-side devices has an overlapping cell order in the checking step. And further comprising:

According to the present invention, in the inserting step, each master station side apparatus inserts the order information of the transmission cell, and in the checking step, each slave station side apparatus extracts the order information in the received cell. Then, the order of each cell is checked, and in the discarding step, each slave station device discards the duplicated cell when the order of the cells is duplicated in the checking step.

[0035]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of a redundant optical multi-branch communication system and method according to the present invention will be described below in detail with reference to the accompanying drawings.

Embodiment 1 First, a first embodiment of the present invention will be described. FIG. 1 is a block diagram showing a configuration of a redundant optical multi-branch communication system according to Embodiment 1 of the present invention. In FIG. 1, in the redundant optical multi-branch communication system 1, the active and standby master stations 10a, 10a are used.
b is connected to the optical splitter 30 by different optical fibers, respectively, and the plurality of slave station apparatuses 20-1 to 20-n are connected to the optical splitter 30 by different optical fibers.
The active master station device 10a broadcasts and distributes the input cells to the slave station devices 20-1 to 20-n via the optical splitter 30, and the slave station devices 20-1 to 20-n. n multiplexes the cells from the slave units 20-1 to 20-n in the optical splitter 30 by setting different delay amounts, and sends the multiplexed cells to the master unit 10a.

Note that the standby system 10b of the standby system can receive cells input via the optical splitter 30, but cannot transmit the cells to the optical splitter 30. The selection circuit 31 is a circuit for selecting cells received by the active and standby master stations 10a and 10b, and is used as the active master station 10a, 1b.
0b is selected and output.

The inter-system delay difference setting sections 17a and 17b of the master station devices 10a and 10b include the optical path length between the master station device 10a and the optical splitter 30, the master station device 10b and the optical splitter 30, respectively. The delay time difference (inter-system delay difference) corresponding to the difference between the optical path length and the optical path length is stored. This delay difference between systems is
It is set in advance by an operation by a system administrator or the like. This delay time difference is determined by each of the master station devices 10a and 10a.
b, an optical signal is sent out and passed through the optical splitter 30,
This is a value corresponding to the time difference when the data is turned back at each of the slave station devices 20-1 to 20-n and transferred to each of the master station devices 10a and 10b via the optical splitter 30.

Transmission / reception section 11 of master station apparatuses 10a and 10b
a and 11b convert an electric signal input by an optical transceiver and a WDM coupler or the like (not shown) into an optical signal and transmit the optical signal to the optical splitter 30;
The optical signal input from the 0 side is converted into an electric signal and output.
However, as described above, the standby master station device 10b
Does not perform transmission output. OAM cell separation unit 12a, 1
2b separates a data cell and an OAM cell from cells input from the slave station side devices 20-1 to 20-n, outputs the data cell to the selection circuit 31, and converts the OAM cell into a delay amount measurement unit. 13a and 13b.

When the delay amount measuring cells returned from the slave units 20-1 to 20-n are present in the OAM cell, the delay amount measuring units 13a and 13b determine the delay amount measuring cells based on the delay amount measuring cells. Measure the round trip time. The delay amount correction units 14a and 14b correct the round trip times measured by the delay amount measurement units 13a and 13b when the active master device 10a and the standby master device 10b are switched. I do.

The value to be corrected is set in the inter-system delay difference setting section 17.
a and 17b. The inter-system delay difference setting unit 17a sets the correction amount to “0” because the master station device 10a is currently the working system and serves as a reference, and the delay amount correction unit 14a uses the delay amount measurement unit 13a No correction is made to the measured round trip time. On the other hand, the inter-system delay difference setting unit 17b sets the correction amount to the inter-system delay difference (delay amount) because the master station device 10b is currently the standby system.
The delay amount correction unit 14b sets the delay amount measurement unit 1
A correction for adding a delay difference between systems to the round trip time measured by 3b is performed.

The delay measurement cell generators 15a and 15b
If the delay-corrected value is a minute change within a predetermined threshold, the delay-corrected delay is corrected and the delay-amount notification cell is sent to each of the slave station devices 20-1 to 20-n. OAM
Transmit as a cell. On the other hand, the delay amount measurement cell generation unit 15
a and 15b indicate that each of the slave station apparatuses 20-1 to 20-1 has a variation in which the delay-corrected value exceeds a predetermined threshold value.
A delay amount measurement cell indicating the re-measurement of the delay amount measurement is transmitted as an OAM cell to 20-n. Note that the delay amounts transmitted by the delay amount measurement cell generation units 15a and 15b are 値 of the delay amounts (round trip time differences) corrected by the delay amount correction units 14a and 14b. This is because the amount of delay set by each of the slave station devices 20-1 to 20-n is for performing delay control of uplink cells.

On the other hand, the transmitting / receiving section 21 of each of the slave station devices 20-1 to 20-n converts an optical signal received by an optical transceiver (not shown) and a WDM coupler or the like into an electric signal, and outputs the electric signal. To the master station side device 10
a, 10b. The frame synchronization unit 22 synchronizes the frames based on the frame synchronization bits in the OAM cells inserted periodically. The OAM cell separation unit 23 recognizes the break of each cell, and identifies and separates the data cell and the OAM cell addressed to the local station device 20-1. When a delay amount cell exists in the separated OAM cells, the delay amount setting unit 24 immediately notifies the OAM cell insertion unit 26, and transmits a delay amount measurement cell as a response through the transmission / reception unit 21 to the master station side device. 10a, 10b, and the delay amount measurement units 13a,
13b makes it possible to measure the round trip time.

On the other hand, the delay amount setting unit 24
When a delay amount notification cell is included in the AM cell, this delay amount is set as a control amount of the read time for the buffer memory 125. As a result, the delay of the transmission timing from the slave station side device 20-1 to the master station side devices 10a and 10b is controlled, the multiplexing is performed in an orderly manner, and the upstream optical transmission is performed normally.

The master station devices 10a and 10b have frame counters 18a and 18b and delay units 19a and 19b.
The transmission timing of the downstream optical signal to 1 to 20-n is controlled. The active frame counter 18a is self-running, and the standby frame counter 18b is subordinately synchronized with the active frame counter 18a. Standby system side station device 10b
Is switched to the active system, the standby frame counter 18b runs by itself, and the active frame counter 18a
Synchronizes with the standby frame counter 18b.

When the standby system 18b in the standby system is switched to the active system, the frame counter 18b runs by itself, and the delay unit 19b sets 1/1/1 of the inter-system delay difference set by the inter-system delay difference setting unit 17b. The frame synchronization whose phase is shifted by the delay amount of 2 is transmitted to the transmission / reception unit 11b. by this,
Even when the standby system 10b of the standby system is switched to the active system, at the point of the optical splitter 30, the reception timing of the cell transmitted from the active system 10a which was the active system and the switching from the standby system to the active system are performed. Master station device 10b switched to
This coincides with the reception timing of the cell transmitted from, and the delay control of the downstream optical signal has been performed.

Here, the processing procedure of the redundant optical multi-branch communication method according to the first embodiment will be described with reference to the sequence diagram shown in FIG. In FIG. 2, the inter-system delay difference setting unit 1 of the active and standby master stations 10a and 10b.
The optical splitter 30 and the master device 10
a, and an inter-system delay difference corresponding to an optical path difference between the optical splitter 30 and the master device 10b is set in advance (steps S101 and S102). In this case, the inter-system delay difference setting unit 17a sets the correction amount for the delay amount correction unit 14a to “0”, and the inter-system delay difference setting unit 17b sets the correction amount for the delay amount correction unit 14b to the inter-system delay difference. Set as Thereafter, with the start-up of the system, the frame counter 18a runs by itself (step S103), and the frame counter 18b is subordinately synchronized with the frame counter 18a (step S104).

Thereafter, the active master station device 10a sends the delay amount measurement cell to each of the slave station devices 20-1 to 20-n, whereby the slave station devices 20-1 to 20-n are transmitted.
-N to start delay measurement (step S10).
5). Slave station side devices 20-1 to -20 that have received the delay amount measurement cell
20-n immediately returns the delay amount measurement cell to the parent device 10a (step S106). The master device 10a, which has received the returned delay amount measurement cell,
3a, the delay amount is measured (step S107), and the delay amount measurement cell generation unit 15a sends a delay amount notification cell to each of the slave station devices 20-1 to 20-n based on the delay amount measurement result. Generate and send out (step S108).

The delay setting unit 24 of each of the slave units 20-1 to 20-n that has received the delay notification cell sets the delay with respect to the buffer memory 25 and controls the transmission timing of the uplink data ( Step S109). afterwards,
The transmission data from each of the slave station devices 20-1 to 20-n is:
The delay is controlled by the buffer memory 25, multiplexed, and transmitted to the parent device 10a. Thereafter, the master device 10a appropriately corrects the delay amount (step S11).
0) To enable good optical multi-branch communication.

Here, due to a line failure or forced switching, etc., the active master station device 10a and the standby master station device 1
If switching to 0b has occurred (step S111), the standby master station device 10b starts transmission output (step S112) and performs transmission timing correction (step S113). The transmission timing correction is to adjust the timing of the frame synchronization phase performed by the frame counter 18b, the delay unit 19b, and the inter-system delay difference setting unit 17b.

Thereafter, when data is received from the slave station side devices 20-1 to 20-n, the delay amount measurement unit 13b measures the delay amount based on the delay amount measurement cell, and furthermore, the delay amount correction unit 14b, the delay amount corresponding to the inter-system delay difference set in the inter-system delay difference setting unit 17b is added, and the delay amount measurement cell generation unit 15b uses the amount of delay to
The delay amount for -1 to 20-n is included in the delay amount notification cell and transmitted (step S114). The delay amount setting unit 24 of the slave station devices 20-1 to 20-n that has received the delay amount notification cell changes the delay amount in the delay amount notification cell as the delay amount for the buffer memory 25 (step S1).
15). Thereafter, the slave station devices 20-1 to 20-n send the uplink data at the changed sending timing, and the master device 10b corrects the delay amount (step S116).

In the first embodiment, when the standby system of the standby system is switched to the active system, the inter-system delay difference preset by the inter-system delay difference setting unit 17b of the standby system is immediately corrected. Is performed, the delay amount set in each of the slave station devices 20-1 to 20-n hardly changes before and after the switching, and the slave station devices 20-1 to 20-1 to 20-n are not changed from the master station device 10b. The delay amount in the downlink direction to 20-n is also immediately corrected by the delay unit 19b, so that re-ranging associated with switching need not be performed, switching can be performed at high speed, and instantaneous interruption time associated with switching can be reduced. it can.

Next, a second embodiment of the present invention will be described. In the first embodiment, the standby frame counter 18b is subordinately synchronized with the active frame counter 18a, and when the standby master station device 10b is switched to the active system, the frame counter 18b is set to self-running. ,
Although the frame synchronization is delayed by the delay unit 19b by the inter-system delay difference set in the inter-system delay difference setting unit 17b, the data transmission timing in the downstream direction is corrected by this. In the second embodiment, , Transmitting and receiving unit 11
A memory is provided at a stage preceding a and 11b, and the timing of the transmission cell is controlled by controlling the amount of memory in the memory, thereby correcting the inter-system delay difference.

FIG. 3 is a block diagram showing a configuration of a redundant optical multi-branch communication system according to the second embodiment of the present invention. In FIG. 3, each of the master station devices 10a and 10b includes:
The memories 41a, 41b are provided before the transmitting / receiving units 11a, 11b.
Is newly provided. These memories 41a and 41b
Is the frame counter 18a, 1 in the first embodiment.
8b and a function corresponding to the delay units 19a and 19b. The configuration is the same as that of the first embodiment except that the memories 41a and 41b are provided instead of the frame counters 18a and 18b and the delay units 19a and 19b. The same components are given the same reference numerals.

Control switching of the cell transmission timing by the memories 41a and 41b is performed at the time of transmission timing correction (step S113) shown in FIG. 2, and the other processing procedures are the same as those in the first embodiment. That is, the working system memory 41a sets the inter-system delay difference to "0" and does not perform the downstream delay difference correction, and the standby system memory 41b stores the inter-system delay difference setting unit 17b when switching to the working system. , And the memory amount to be delayed is controlled.

In the second embodiment, the memories 19a, 1
Since the cell transmission timing is controlled by controlling the memory amount for 9b, a simple configuration allows
As in the first embodiment, it is not necessary to perform the re-ranging associated with the switching, the switching can be performed at high speed, and the instantaneous interruption time associated with the switching can be reduced.

Next, a third embodiment of the present invention will be described. In Embodiments 1 and 2 described above, when switching between the active system and the standby system, the cell transmission timing in the downlink and the cell transmission timing in the uplink are corrected based on a preset inter-system delay difference. Although the switching time is shortened without performing the ranging, in the third embodiment, at the time of the switching, the delay amount corresponding to the inter-system delay difference is changed from the master station devices 10a and 10b to the slave station device 20-1. Switching is performed quickly by notifying immediately to .about.20-n.

FIG. 4 is a block diagram showing a configuration of a redundant optical multi-branch communication system according to the third embodiment of the present invention. In FIG. 4, each of the master station devices 10a and 10b includes:
Switch cell switching cell generators 51a and 51b for notifying the delay amount when switching from the active system to the standby system are further provided, and the delay amount correctors 14a and 14b, the frame counters 18a and 18b, and the delay unit 19a according to the first embodiment are provided. , 1
9b is omitted. Also, the slave station device 20
A switching cell receiving unit 52 is newly provided in -1 to 20-n. Other configurations are the same as those of the first embodiment, and the same components are denoted by the same reference numerals.

When the switching from the working system to the protection system is performed, the switching cell generators 51a and 51b are connected to each of the slave station devices 2a.
0-1 to 20-n, the inter-system delay difference setting units 17a, 1
A switching cell including the inter-system delay difference set in 7b is transmitted. On the other hand, when receiving the switching cell, the switching cell receiving unit 52 of each of the slave station apparatuses 20-1 to 20-n receives the switching cell.
, The delay amount corresponding to the inter-system delay difference in the switching cell is reset.

Here, a processing procedure of the redundant optical multi-branch communication method according to the third embodiment will be described with reference to a sequence diagram shown in FIG. In FIG. 5, the inter-system delay difference setting unit 1 of the active and standby master stations 10a and 10b.
The optical splitter 30 and the master device 10
a, and an inter-system delay difference corresponding to an optical path difference between the optical splitter 30 and the master device 10b is set in advance (steps S201 and S202). In this case, the inter-system delay difference setting unit 17a sets the correction amount for the delay amount correction unit 14a to “0”, and the inter-system delay difference setting unit 17b sets the correction amount for the delay amount correction unit 14b to the inter-system delay difference. Set as

Thereafter, the active master station device 10a sends the delay amount measurement cell to each of the slave station devices 20-1 to 20-n, whereby the slave station devices 20-1 to 20-n are transmitted.
-N to start delay measurement (step S20)
3). Slave station side devices 20-1 to -20 that have received the delay amount measurement cell
20-n immediately returns the delay amount measurement cell to the parent device 10a (step S204). The master device 10a, which has received the returned delay amount measurement cell,
3a, the delay amount is measured (step S205), and the delay amount measurement cell generation unit 15a sends a delay amount notification cell to each of the slave station devices 20-1 to 20-n based on the delay amount measurement result. Generate and send (step S206).

The delay setting unit 24 of each of the slave units 20-1 to 20-n that has received the delay notification cell sets the delay with respect to the buffer memory 25 and controls the transmission timing of the uplink data ( Step S207). afterwards,
The transmission data from each of the slave station devices 20-1 to 20-n is:
The delay is controlled by the buffer memory 25, multiplexed, and transmitted to the parent device 10a. Thereafter, the master station side device 10a appropriately corrects the delay amount (Step S20).
8) To enable good optical multi-branch communication.

Here, due to a line failure or forced switching, etc., the active master station device 10a and the standby master station device 1 are switched.
0b, first, the active master station device 10
From a, the switching cell is transmitted to the slave station devices 20-1 to 20-n (step S209). Slave station side devices 20-1 to 20
-N receives the switching cell in the switching cell receiving unit 52,
Preparation for changing the delay amount is performed by the delay amount setting unit 24 (step S210). Thereafter, switching from the active master station device 10a to the standby master device 10b is performed (step S211), and the standby master device 10b that has become the active system is switched.
Sends the switching cell including the information on the inter-system delay difference generated by the switching cell generation unit 51b to the slave station devices 20-1 to 20-n (step S212).

The slave units 20-1 to 20-n synchronize the frame based on the synchronization bit in the switching cell transmitted from the master unit 10b, and set the delay amount setting unit 24.
Changes the delay amount for the buffer memory 25 (step S213). As a result, the delay amount correction accompanying the switching between the active system and the standby system is performed, and thereafter, the slave unit 2
When the data is received from 0-1 to 20-n, the delay amount measurement unit 13b measures the delay amount based on the delay amount measurement cell, and appropriately performs the delay amount correction (step S214).

According to the third embodiment, when the standby system of the standby system is switched to the active system, the inter-system delay difference preset by the inter-system delay difference setting unit 17b of the standby system is used. The switching cell including the slave station device 20-1 to 20-n is immediately transmitted to change the delay amount of the slave station device, and the delay amount correction corresponding to the delay amount correction in the downlink direction is performed by the slave station device 2.
Since the re-synchronization of frames 0-1 to 20-n is performed, switching can be performed at high speed without performing re-ranging due to switching, and instantaneous interruption due to switching is performed, as in the first and second embodiments. Time can be reduced.

Next, a fourth embodiment of the present invention will be described. In Embodiment 3 described above, the delay amount correction in the downlink direction is performed by the frame resynchronization process by the local station side devices 20-1 to 20-n. After switching to the system, the frame synchronization is forcibly reset to reduce the time required for frame resynchronization.

FIG. 6 is a block diagram showing a configuration of a redundant optical multi-branch communication system according to the fourth embodiment of the present invention. In FIG. 6, the switching cell receiving unit 53 of each of the slave station devices 20-1 to 20-n is configured to forcibly reset the frame synchronization by the frame synchronizing unit 22 when receiving the switching cell. Other configurations are the same as those of the third embodiment, and the same components are denoted by the same reference numerals.

FIG. 7 is a sequence diagram showing a processing procedure of the redundant optical multi-branch communication method according to the fourth embodiment. FIG.
In steps S301 to S308, the same processing as steps S201 to S208 in the third embodiment is performed.

When switching between the active master device 10a and the standby master device 10b due to a line failure or forced switching, etc., first, the switching cell is transferred from the working master device 10a to the slave station. It is sent to the side devices 20-1 to 20-n (step S309). The slave station devices 20-1 to 20-n are:
The switching cell is received by the switching cell receiving unit 53, and the delay amount setting unit 24 prepares to change the delay amount (step S31).
0). In particular, the switching cell receiving unit 53 includes the frame synchronization unit 2
2 forcibly reset the frame synchronization (step S
311). As a result, the frame synchronization is lost for a certain period of time, and then the frame synchronization unit 22 searches again for the frame synchronization position from around the frame synchronization position before the synchronization reset.

Thereafter, switching from the active master station device 10a to the standby master station device 10b is performed (step S).
312), the standby master station device 10b that has become the active system
Sends the switching cell including the information of the inter-system delay difference from the switching cell generation unit 51b to the slave station devices 20-1 to 20-n (step S313). Slave station side devices 20-1 to 20-n
Performs the above-described frame resynchronization based on the synchronization bit in the switching cell transmitted from the master station device 10b, and the delay amount setting unit 24 changes the delay amount for the buffer memory 25 (step S314). . As a result, the delay amount correction accompanying the switching between the active system and the standby system is performed, and thereafter, when data is received from the slave station devices 20-1 to 20-n, the delay amount measurement unit 13b sets the delay amount The delay amount is measured based on the measurement cell, and the delay amount is appropriately corrected (step S315).

According to the fourth embodiment, slave unit 2
Since the frame resynchronization of 0-1 to 20-n is performed after the forced reset of the frame synchronization, the time required for the frame resynchronization can be shortened, and as a result, the reranging accompanying the switching is performed. Switching can be performed at high speed without
The instantaneous interruption time accompanying the switching can be reduced.

Next, a fifth embodiment of the present invention will be described. In the above-described first to fourth embodiments, switching between the active system and the standby system is performed quickly, but instantaneous interruption of data at the time of switching cannot be avoided. In the fifth embodiment, the instantaneous data interruption in the down direction at the time of switching is prevented.

FIG. 8 is a block diagram showing a configuration of a redundant optical multi-branch communication system according to the fifth embodiment of the present invention. In FIG. 8, each of the master-station-side devices 10a and 10b
AM cell insertion units 16a, 16b and memories 41a, 41b
And cell order insertion sections 61a and 61b.
Further, each of the slave station devices 20-1 to 20-n includes a cell discard unit 6 between the frame synchronization unit 22 and the OAM cell separation unit 23.
3 and a cell order checking unit 62 is provided in parallel between the frame synchronization unit 22 and the cell discarding unit 63.
Other configurations are the same as those of the second embodiment, and the same components are denoted by the same reference numerals.

The cell order insertion units 61a and 61b
The cell order information is inserted into the cells input via the cell insertion units 16a and 16b. The cell order checking unit 62 checks the order information inserted in the cell input via the frame synchronization unit 22, and when there is a cell having overlapping order information, the cell discarding unit 63 An instruction is given to discard one cell, and the cell discarding unit 63 discards the cell when instructed to discard the cell. The inter-system delay difference setting unit 17b sets the transmission timing of the standby master device 10b at the position of the optical splitter 30 so as to always be delayed from the transmission timing of the active master device 10a. .

According to the fifth embodiment, when switching between the active system and the standby system, the cell transmission timing of the standby system that has been switched to the active system is set at the position of the optical splitter 30 and the master station apparatus that was the active system. Since the cell transmission timing from the cell 10a is always delayed and the duplicated cells are discarded, it is possible to prevent the cell drop in the down direction at the time of switching.

Next, a sixth embodiment of the present invention will be described. In the above-described first to fifth embodiments, the inter-system delay difference setting unit 17a, 17b sets the inter-system delay difference in advance by operation. In the sixth embodiment, however, the parent of the standby system is set. The inter-system delay difference is dynamically counted based on the cell received by the optical line terminal 10b, and when the switching between the working system and the standby system occurs, the counted inter-system delay difference is used. .

FIG. 9 is a block diagram showing a configuration of a redundant optical multi-branch communication system according to the sixth embodiment of the present invention. In FIG. 9, each of the master-station-side devices 10a and 10b is newly provided with inter-system delay difference counting units 71a and 71b instead of the inter-system delay difference setting units 17a and 17b. Other configurations are the same as those of the third embodiment, and the same components are denoted by the same reference numerals.

The standby-system side device 10b is, like the working-type master-side device 10a, each of the slave-side devices 20-1 to 20-20.
−n can be received via the optical splitter 30. Thus, the inter-system delay difference counting unit 71b counts the difference between the round trip time measured by the delay difference measurement unit 13b and the round trip time measured by the delay difference measurement unit 13a of the working system, that is, the inter-system delay difference.

On the other hand, the inter-system delay difference counting section 71a calculates an inter-system delay difference which is a difference between the round trip time measured by the delay difference measuring section 13a and the round trip time measured by the delay difference measuring section 13b of the standby system. Count. When the standby-system side device 10b of the standby system is switched to the active system, the switching cell generation unit 51b generates a switching cell using the inter-system delay difference counted by the inter-system delay difference counting unit 71b, and sets each of the switching cells as an OAM cell. The data is transmitted to the slave station devices 20-1 to 20-n.

Here, a processing procedure of the redundant optical multi-branch communication method according to the sixth embodiment will be described with reference to a sequence diagram shown in FIG. In FIG. 10, an active master station device 10a stores a delay amount measurement cell in each slave station device 20a.
The delay measurement for each of the slave station devices 20-1 to 20-n is started by transmitting the signals to -1 to 20-n (step S401). The slave units 20-1 to 20-n that have received the delay measurement cell are immediately changed to the master unit 10a.
(Step S402). The master station device 10a, which has received the returned delay amount measurement cell,
10b measures the delay amount by the delay amount measurement units 13a and 13b, respectively, and the delay amount measurement units 13a and 13b output the measured delay amount to the delay amount measurement cell generation units 15a and 15b, respectively, Difference counting section 71b,
The measured delay amount is transmitted to 71a (step S40).
3).

The inter-system delay difference counting unit 71a counts the inter-system delay difference, which is the difference between the delay amount notified from the delay amount measurement unit 13a and the delay amount notified from the delay amount measurement unit 13b, and It is sent to the generation unit 51a, and the inter-system delay difference counting unit 71b
Counts the inter-system delay difference, which is the difference between the delay amount notified from the delay amount measurement unit 13b and the delay amount notified from the delay amount measurement unit 13a, and sends the difference to the switching cell generation unit 51b (step S404). . The inter-system delay difference counting units 71a, 71
The inter-system delay difference counted by b is used at the time of switching.

The delay amount measuring cell generation unit 15a receives the delay amount measurement result of the delay amount measuring unit 13a, and
A delay amount notification cell is generated and transmitted for -1 to 20-n (step S405). The delay amount setting unit 2 of each of the slave station devices 20-1 to 20-n that has received the delay amount notification cell.
4 sets the delay amount for the buffer memory 25 and controls the transmission timing of the uplink data (step S40).
6). Thereafter, the transmission data from each of the slave station devices 20-1 to 20-n is delay-controlled by the buffer memory 25, multiplexed, and sent to the master station device 10a. After that, the master device 10a appropriately corrects the delay amount (step S407) so that the optical multi-branch communication can be performed well.

Here, due to a line failure or forced switching, etc., the active master station device 10a and the standby master station device 1 are switched.
0b, first, the active master station device 10
From a, the switching cell is transmitted to the slave station devices 20-1 to 20-n (step S408). Slave station side devices 20-1 to 20
-N receives the switching cell in the switching cell receiving unit 52,
Preparation for changing the delay amount is performed by the delay amount setting unit 24 (step S409). Thereafter, switching from the active master station apparatus 10a to the standby master station apparatus 10b is performed (step S410), and the standby master station apparatus 10b becomes the active system.
Sends the switching cell including the information of the inter-system delay difference generated by the switching cell generation unit 51b to the slave station devices 20-1 to 20-n (step S411).

In this case, the switching cell generator 51b uses the inter-system delay difference counted by the inter-system delay difference counting unit 71b. The slave units 20-1 to 20-n perform frame synchronization based on the synchronization bit in the switching cell transmitted from the master unit 10b, and the delay amount setting unit 24 determines the delay with respect to the buffer memory 25. The amount is changed (step S41)
2). Thereby, the delay amount correction accompanying the switching between the active system and the standby system is performed, and thereafter, the slave station devices 20-1 to 20-20
-N, the delay amount measurement unit 13b
Measures the delay amount based on the delay amount measurement cell, and appropriately performs the delay amount correction (step S413).

According to the sixth embodiment, since the inter-system delay difference is dynamically measured after the system is started, the inter-system delay difference is more accurate than the inter-system delay difference corresponding to the optical path difference. The difference can be used to perform the delay difference correction accompanying the switching, and the labor and time for setting the inter-system delay difference can be reduced.

In the first to sixth embodiments, the master station devices 10a and 10b are physically separated from each other. However, the present invention is not limited to this.
Obviously, the present invention can be applied to transmission line switching in the case where the optical fibers a and 10b are connected by different optical fibers. It is clear that the above-described first to sixth embodiments may be appropriately combined.

[0087]

As described above, according to the present invention, the holding means for the active and standby master units is provided by the active and standby master units. The round trip optical delay time, which is returned from the slave device to the slave device via the optical splitter and transferred to the working master device again, and the slave from the standby master device via the optical splitter. The return is made by the optical line terminal, and the optical delay time difference from the round trip optical delay time transferred to the parent system of the standby system is held again.The transmission control means switches the standby system of the standby system to the active system. In this case, the optical signal to be transmitted to each slave station side device is transmitted after performing delay correction corresponding to the optical delay time difference, and the delay amount correcting means switches the standby system of the standby system to the active system. The delay amount for each slave station side device when the Performs settings to correct in advance in accordance with the time difference, corrects the delay difference in the uplink and downlink directions when the active system and the standby system are switched, and performs normal optical multi-branch communication without performing re-ranging. As a result, switching between the active system and the standby system can be performed at high speed, and the effect of reducing the instantaneous interruption time associated with the switching can be achieved.

According to the next invention, the transmission control means includes a frame counter, and when the own master station apparatus is the standby system, the frame counter of the own master station apparatus is used for the active master station apparatus. The slave station side-synchronizes with the frame counter, runs when the own master station side apparatus is switched to the active system, and the transmission control means of the standby system sets the phase of the frame counter of the standby system to correspond to the optical delay time difference. An optical signal is transmitted in synchronization with the delayed frame counter, and before and after switching, delay correction is performed to match the transmission timing in the down direction at the position of the optical splitter. Switching can be performed at high speed, and an effect of shortening the instantaneous interruption time accompanying the switching can be achieved.

According to the next invention, the transmission control means includes a memory in front of the transmission means for transmitting the optical signal, and the transmission control means controls the amount of memory of the memory so that the transmission timing of the optical signal is controlled. Is delayed in accordance with the optical delay time difference, and delay correction is performed to match the downstream transmission timing at the position of the optical splitter, so that switching between the active system and the standby system can be performed at high speed. This has the effect that the instantaneous interruption time associated with switching can be reduced.

According to the next invention, the holding means of the working system and the protection system of the master station device returns from the master system device of the working system to the slave device via the optical splitter.
The round trip optical delay time transferred again to the active master device and the standby master device from the standby system are looped back by the slave device via the optical splitter, and again to the standby master device. The optical delay time difference from the transferred round-trip optical delay time is held, and the notifying means sends the information including the optical delay time difference to each slave station side device when the standby master device is switched to the active system. The delay control means of the slave station device resets the delay amount in consideration of the optical delay time difference notified by the notification means, controls the transmission timing of the optical signal to be sent to the master station device, and When the system and the standby system are switched, the delay difference in the downstream direction is corrected for delay by frame resynchronization, the delay difference in the upstream direction is corrected by delay control means, and normal optical multi-branch communication is performed without performing re-ranging. Because I do The switching between the active system and a standby system can be performed at high speed, an effect that it is possible to shorten the instantaneous interruption time associated with switching.

According to the next invention, when the reset means of each slave station device receives information including the optical delay time difference,
The frame synchronization for receiving the optical signal transmitted from the master station is forcibly reset, and the frame is resynchronized after the switching, so that the frame synchronization time is shortened, and the switching between the active system and the standby system is performed. Can be performed at high speed, and the instantaneous interruption time accompanying the switching can be shortened.

According to the next invention, the inserting means of each master station device inserts the order information of the sending cell into the sending cell, and the checking means of each slave station device checks the order in the received cell. The information is extracted and the order of each cell is checked, and the discarding unit discards the duplicated cell when the order of the cells is duplicated by the checking unit. Even when frame synchronization is lost, there is an effect that switching can be performed without cell loss.

According to the next invention, by the holding step,
The round trip optical delay time from the working master station device via the optical splitter to the slave station device via the optical splitter and transferred again to the working master device, and the standby master device from the protection system. Returned by the local station side device via the optical splitter,
The optical delay time difference between the round trip optical delay time and the round trip optical delay time transferred to the standby master device again is held,
When the standby-system side device of the standby system is switched to the active system, the delay amount for each of the slave-station-side devices is set to be corrected in advance in accordance with the optical delay time difference. The optical signal to be sent to each slave station device when the master station device is switched to the working system is transmitted after performing the delay correction corresponding to the optical delay time difference, and by the notification step, Based on the delay amount of the optical signal sent from the side device, the delay amount set in the delay amount correction step is corrected and notified to each slave station side device, and the working system and the standby system are switched. In the case, the delay difference in the upstream and downstream directions is corrected, and normal optical multi-branch communication is performed without performing re-ranging, so that switching between the working system and the standby system can be performed at high speed, The instantaneous interruption time associated with switching can be reduced. There is an effect that that.

According to the next invention, the transmission control step makes the frame counter of the own master station apparatus dependently synchronized with the frame counter of the working master station apparatus when the own master station apparatus is the standby system. When the own master station apparatus is switched to the active system, it runs by itself, delays the phase of the frame counter of the own master station apparatus in accordance with the optical delay time difference, and synchronizes with the delayed frame counter. Since the optical signal is transmitted, and before and after the switching, delay correction is performed to match the transmission timing in the down direction at the position of the optical splitter, so that the switching between the working system and the standby system can be performed at high speed. This has the effect that the instantaneous interruption time associated with switching can be reduced.

According to the next invention, the transmission control step delays the transmission timing of the optical signal having the transmission information in accordance with the optical delay time difference by controlling the memory amount of the memory for storing the transmission information. Since the delay correction is performed so as to match the downstream transmission timing at the position of the optical splitter, the switching between the active system and the standby system can be performed at high speed, and the instantaneous interruption time accompanying the switching can be reduced. It has the effect of being able to do so.

According to the next invention, by the holding step,
The round trip optical delay time from the working master station device via the optical splitter to the slave station device via the optical splitter and transferred again to the working master device, and the standby master device from the protection system. Returned by the local station side device via the optical splitter,
The optical delay time difference from the round-trip optical delay time transferred to the standby master device again is held, and when the standby master device is switched to the working system by the notification process, the standby system is switched to the standby system. The master device notifies the slave device of the information including the optical delay time difference, and by the delay control step, the slave device sets the delay amount in consideration of the optical delay time difference notified by the notification process. Reset and control the transmission timing of the optical signal to be transmitted to the master station side device, thereby, when the active system and the standby system are switched, the delay difference in the downlink direction is corrected by the frame resynchronization, and the delay is corrected. Since the delay difference in the upstream direction is corrected by the delay control process and normal optical multi-branch communication is performed without performing re-ranging,
Switching between the active system and the standby system can be performed at a high speed, and the effect of shortening the instantaneous interruption time due to the switching can be achieved.

According to the next invention, when each slave device receives information including the optical delay time difference in the reset step, each slave device receives the optical signal for transmission from the master device. Since the frame synchronization is reset and the frame is resynchronized after the switching, the frame synchronization time is shortened, the switching between the active system and the standby system can be performed at high speed, and the instantaneous interruption time accompanying the switching is reduced. This has the effect of being able to be shortened.

According to the next invention, by the inserting step,
Each master station side device inserts the order information of the transmission cell, and in the inspection step, each slave station side device extracts the order information in the received cell to check the order of each cell, and in the discarding step, Since each slave station device discards the duplicated cell when the cell order is duplicated by the inspection process, the frame synchronization is lost when switching between the active system and the standby system. Also, there is an effect that switching can be realized without causing a cell drop.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of a redundant optical multi-branch communication system according to a first embodiment of the present invention.

FIG. 2 is a sequence diagram showing a redundant optical multi-branch communication method according to the first embodiment of the present invention.

FIG. 3 is a block diagram illustrating a configuration of a redundant optical multi-branch communication system according to a second embodiment of the present invention;

FIG. 4 is a block diagram illustrating a configuration of a redundant optical multi-branch communication system according to a third embodiment of the present invention;

FIG. 5 is a sequence diagram showing a redundant optical multi-branch communication method according to a third embodiment of the present invention.

FIG. 6 is a block diagram showing a configuration of a redundant optical multi-branch communication system according to a fourth embodiment of the present invention.

FIG. 7 is a sequence diagram showing a redundant optical multi-branch communication method according to a fourth embodiment of the present invention.

FIG. 8 is a block diagram showing a configuration of a redundant optical multi-branch communication system according to a fifth embodiment of the present invention.

FIG. 9 is a block diagram showing a configuration of a redundant optical multi-branch communication system according to a sixth embodiment of the present invention.

FIG. 10 is a sequence diagram showing a redundant optical multi-branch communication method according to a sixth embodiment of the present invention.

FIG. 11 is a block diagram illustrating a schematic configuration of a conventional optical multi-branch communication system.

12 is a block diagram illustrating a detailed configuration of a master station device and a slave station device of the optical multi-branch communication system illustrated in FIG. 11;

FIG. 13 is a block diagram illustrating a schematic configuration of a redundant optical multi-branch communication system.

[Explanation of symbols]

1-6 Redundant optical multi-branch communication system, 10a, 10b
Master station side device, 11a, 11b, 21 transmitting / receiving section, 12
a, 12b OAM cell separation unit, 13a, 13b, 23
Delay amount measuring unit, 14a, 14b Delay amount correcting unit, 15
a, 15b Delay amount measurement cell generator, 16a, 16b,
26 OAM cell insertion unit, 17a, 17b delay difference setting unit between systems, 18a, 18b Frame counter, 19a, 1
9b delay unit, 20-1 to 20-n slave unit, 22
Frame synchronization unit, 24 delay amount setting unit, 25 buffer memory, 30 optical splitter, 31 selection circuit, 41
a, 41b memory, 51a, 51b switching cell generating unit, 52, 53 switching cell receiving unit, 61a, 61b cell order inserting unit, 62 cell order checking unit, 63 cell discarding unit, 71a, 71b inter-system delay difference counting unit.

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Yoshihiro Asaba 2-3-2 Marunouchi, Chiyoda-ku, Tokyo F-term (reference) 5M002 AA05 BA04 BA05 DA03 DA12 EA33 FA01 5K014 AA01 CA03 CA06 EA05 FA01 5K033 CA11 CB03 CB06 CB13 CB15 DA01 DA15 DB02 DB12 DB22 EA02 EA06 EA07 EB06 EC01

Claims (12)

[Claims] An optical splitter connects an active-system and standby-system master device to a plurality of slave-station devices, and at least one of the working-system and standby-system master devices is connected to one or more optical communication lines. The working master station device broadcasts and distributes an optical signal to each slave station device by the optical splitter, and the working master station device round-trips to each slave station device. Measuring the time, notifying the round trip time to each slave station side device, and setting the timing of transmitting the optical signal by each slave station device in accordance with each of the notified round trip times, thereby setting the working system. In the redundant optical multi-branch communication system that is time-division multiplexed connected to the master station device, the working system and the protection master device are connected to each other from the working master device via the optical splitter. Return at the station side device , Folded in daughter devices via the optical splitter from the parent device of the standby system with round trip optical delay time transferred to parent device of the developing for system again,
Holding means for holding an optical delay time difference between the round trip optical delay time and the round trip optical delay time transferred to the standby system again, and each slave unit when the standby system is switched to the active system. Transmission control means for performing a delay correction corresponding to the optical delay time difference and transmitting the optical signal to be transmitted to the slave station device when the standby master device is switched to a working system. And a delay amount correcting means for performing a setting for correcting in advance the delay amount corresponding to the optical delay time difference in accordance with the optical delay time difference. 2. The transmission control means includes a frame counter, and when the own master station apparatus is a standby system, the frame counter of the own master station apparatus is dependent on the frame counter of the working master station apparatus. Synchronously, when the own master station side apparatus is switched to the working system, it runs by itself, and the transmission control means of the standby system,
2. The redundant optical multi-branch communication according to claim 1, wherein a phase of the standby frame counter is delayed in accordance with the optical delay time difference, and the optical signal is transmitted in synchronization with the delayed frame counter. system. 3. The transmission control means includes a memory in front of the transmission means for transmitting the optical signal, and the transmission control means controls a transmission amount of the optical signal by controlling a memory amount of the memory. 2. The redundant optical multi-branch communication system according to claim 1, wherein the delay is performed in accordance with the optical delay time difference. 4. The active and standby master devices and a plurality of slave devices are connected by an optical splitter, and at least one of the active and standby master devices is connected to at least one optical communication line. The working master station device broadcasts and distributes an optical signal to each slave station device by the optical splitter, and the working master station device round-trips to each slave station device. Measuring the time, notifying the round trip time to each slave station side device, and setting the timing of transmitting the optical signal by each slave station device in accordance with each of the notified round trip times, thereby setting the working system. In the redundant optical multi-branch communication system that is time-division multiplexed connected to the master station device, the working system and the protection master device are connected to each other from the working master device via the optical splitter. Return at the station side device , Folded in daughter devices via the optical splitter from the parent device of the standby system with round trip optical delay time transferred to parent device of the developing for system again,
Holding means for holding an optical delay time difference from the round trip optical delay time transferred to the standby master device again, and the optical delay time difference when the standby master device is switched to the working system. Notification means for notifying each slave station apparatus of the information including the information, and wherein each slave station apparatus resets the delay amount in consideration of the optical delay time difference notified by the notification means, and sets the master station apparatus. 1. A redundant optical multi-branch communication system, comprising: delay control means for controlling the transmission timing of an optical signal to be transmitted to a communication system. 5. The apparatus according to claim 1, wherein each of the slave station apparatuses further includes a reset unit configured to reset frame synchronization for receiving an optical signal transmitted from the master station apparatus when the information including the optical delay time difference is received. The redundant optical multi-branch communication system according to claim 4, wherein: 6. Each of the master station devices further includes an insertion unit for inserting order information of the sending cell into a sending cell, and each of the slave station devices extracts the order information in a received cell. 6. An inspecting means for inspecting the order of each cell by using the inspecting means, and a discarding means for discarding the duplicated cell when the order of the cells is duplicated by the inspecting means. The redundant optical multi-branch communication system according to any one of the above. 7. The active and standby master devices and a plurality of slave devices are connected by an optical splitter, and at least one of the active and standby master devices is connected to at least one optical communication line. The working master station device broadcasts and distributes an optical signal to each slave station device by the optical splitter, and the working master station device round-trips to each slave station device. Measuring the time, notifying the round trip time to each slave station side device, and setting the timing of transmitting the optical signal by each slave station device in accordance with each of the notified round trip times, thereby setting the working system. In the redundant optical multi-branch communication method which is time-division multiplexed connected to the master station device, the slave device returns from the working master device via the optical splitter, and returns to the working master station again. Forwarded to the local device Folded in daughter devices wherein the light delay time from the standby parent device of via the optical splitter,
A holding step of holding an optical delay time difference between the round trip optical delay time and the round trip optical delay time transferred to the standby system again, and each of the slave stations when the standby system is switched to the active system. A delay amount correction step of setting a delay amount for the device to be corrected in advance in accordance with the optical delay time difference, and transmitting the delay amount to each slave station device when the standby master device is switched to the working system. An optical signal, a transmission control step of performing a delay correction corresponding to the optical delay time difference and transmitting the optical signal, and setting by the delay amount correcting step based on a delay amount of the optical signal transmitted from each of the slave station side devices. And a notifying step of correcting the delay amount thus notified to each of the slave station-side devices. 8. The transmission control step, wherein when the own master station apparatus is a standby system, the frame counter of the own master station apparatus is subordinately synchronized with the frame counter of the working master station apparatus,
When the own master station side device is switched to the active system, it runs by itself,
8. The redundancy according to claim 7, wherein a phase of a frame counter of said own master station side device is delayed in accordance with said optical delay time difference, and said optical signal is transmitted in synchronization with said delayed frame counter. Optical multi-branch communication method. 9. The transmission control step delays a transmission timing of an optical signal having the transmission information in accordance with the optical delay time difference by controlling a memory amount of a memory for storing transmission information. The redundant optical multi-branch communication method according to claim 7, wherein 10. A working-side and standby-system master-station-side device and a plurality of slave-station-side devices are connected by an optical splitter, and at least the working-use and standby-system master-station-side devices each have at least one optical communication line. The working-system master station device is
The optical splitter broadcasts and distributes an optical signal to each of the slave devices, the working master device measures a round trip time for each slave device, and determines the round trip time for each slave device. In response to each of the notified round-trip times, each of the slave station devices sets the transmission timing of the optical signal, so that the redundant optical multiplexer which is time-division multiplexed connected to the working master station device. In the branch communication method, the round trip optical delay time returned from the working master device via the optical splitter to the slave device via the optical splitter and transferred to the working master device again, and the standby master device. From the optical line terminal via the optical splitter, loop back at the optical line terminal,
A holding step of holding an optical delay time difference between the round trip optical delay time and the round trip optical delay time transferred to the standby system again, and the standby system master when the standby system is switched to the active system. A notifying step in which the optical line terminal notifies the information including the optical delay time difference to each slave station side device, and each of the slave station side devices resets the delay amount in consideration of the optical delay time difference notified by the notifying step. A delay control step of controlling a transmission timing of an optical signal to be transmitted to the master station side device. 11. When each of the slave station devices receives information including the optical delay time difference, each slave station device resets frame synchronization for receiving an optical signal transmitted from the master station device. The redundant optical multi-branch communication method according to claim 10, further comprising a resetting step. 12. An insertion step in which each of the master-station-side devices inserts order information of a transmission cell, and each of the slave-station-side devices extracts the order information in a received cell to change the order of each cell. 12. The inspection process according to claim 7, further comprising: an inspection process of inspecting, and a discarding process of discarding the duplicated cell when the order of the cells is duplicated by the inspection process. The redundant optical multi-branch communication method according to any one of the above.